Current concepts in the diagnosis of ocular tuberculosis: A narrative review

Abstract

Ocular tuberculosis (OTB) is one of the extrapulmonary manifestations caused by Mycobacterium tuberculosis (Mtb). If untreated, it can result in poor visual prognosis. Prompt diagnosis of OTB is met with challenges. The gold standard for the diagnosis of OTB is the direct demonstration of the Mtb in ocular tissues or ocular fluids either by Ziehl-Neelsen Stain, culture or molecular diagnostic techniques such as polymerase chain reaction. This is onerous owing to the paucibacillary nature of the disease, small quantity of samples, and low sensitivity and specificity of molecular diagnostic tests. Thus, one needs to rely on indirect evidences to make a diagnosis. Hence, most often, the diagnosis of OTB is presumed based on the geography the patient hails from and indirect laboratory evidences suggestive of TB. In this narrative review, we review clinical, laboratory, and radiology markers which aid in the diagnosis of OTB and outline the current concepts in the diagnosis of OTB.

Keywords: Clinical biomarkers; Mycobacterium tuberculosis; diagnostic tools; ocular tuberculosis.

Figure 1

Anterior segment photograph of an eye with tubercular granulomatous anterior uveitis with broad-based posterior synechiae

Figure 2

Color photograph of an eye with tubercular retinal vasculitis showing chorioretinal scar along the vessel with looping and tortuosity of vessels (white arrow) adjacent the chorioretinal scar (a) and color photograph of the same eyes (b) showing sclerosed vessels with adjacent collaterals (red arrows)

Figure 3

Color photograph of an eye with tubercular retinal vasculitis with active subvascular lesions

Figure 4

Color fundus photograph showing tubercular granuloma with retinal angiomatosis proliferation lesions and exudation before (a) and after treatment (b)

Figure 5

Color photograph showing tubercular granuloma at the macula (a), optical coherence tomography over the lesions shows full thickness choroidal granuloma with outer retinal hyperreflectivity with elevation of the retinal pigment epithelium and disruption of the ellipsoid zone and interdigitation zone described as contact sign (b)

Figure 6

Color photograph of an eye with tubercular multifocal serpiginous choroiditis showing creamy white active lesions at the macula (a), fundus autofluorescence (FAF) of the same eye shows hyperautofluorescence in the macular area suggesting that the lesion is active (b) Color photography at 3 months’ follow-up showing scarring at the macula (c) with FAF showing hypoautofluorescence (d)

Figure 7

Color photograph of the right eye with tubercular multifocal serpiginous choroiditis showing extensive chorioretinal scaring suggestive of healed lesions with few creamy white active lesions (a) color photograph of the left eye of the same patient with showing multiple creamy white active lesions (b)

Figure 8

Anterior segment photograph of a patient with tubercular choroidal granuloma showing corneal scarring with clear area between scar and the limbus